WO2023276521A1

WO2023276521A1 - Aqueous ink composition for ballpoint pens, and ballpoint pen and ballpoint pen refill each including same

Info

Publication number: WO2023276521A1
Application number: PCT/JP2022/021951
Authority: WO
Inventors: 亮山田; 尚嗣中村
Original assignee: 株式会社パイロットコーポレーション
Priority date: 2021-06-28
Filing date: 2022-05-30
Publication date: 2023-01-05
Also published as: JPWO2023276521A1; TW202317714A

Abstract

An aqueous ink composition for ballpoint pens, the ink composition comprising a color pigment, a brilliant pigment, microcapsule particles, a shear-thinning tackifier, and water, wherein, with respect to the total mass of the ink composition, the percentage content of carbon black in the color pigment is 0-2.0 mass%, the percentage content of the brilliant pigment is 0.1-2.0 mass%, and the percentage content of the microcapsule particles is 1.5-10 times of the percentage content of the brilliant pigment.

Description

Water-based ink composition for ball-point pen, and ball-point pen and ball-point pen refill containing same

The present disclosure relates to a water-based ink composition for ballpoint pens, and ballpoint pens and ballpoint pen refills incorporating the same.

Conventionally, water-based ink compositions using luster pigments such as plate-like (scale-like) metal powders or pearl pigments have been actively proposed. While this ink produces bright, gorgeous metallic luster-like handwriting, it uses black pigments such as carbon black and organic pigments as coloring agents, while suppressing the amount of luster pigments added. It is also possible to form lustrous and calm handwriting.

In the ballpoint pen ink using the glitter pigment, the glitter pigment settles and agglomerates in the ink, resulting in a decrease in the ink ejection property, which may make it impossible to write or cause blurring in the handwriting. Studies have been conducted to improve the dispersion stability of organic pigments. (For example, see Patent Document 1)

Patent Document 1 describes an ink containing a metal powder pigment, a coloring material, a natural polysaccharide and a cellulose derivative, and a ballpoint pen containing the ink. This ink maintains a high viscosity when standing still with a shear thinning agent consisting of a natural polysaccharide and a cellulose derivative. The ink achieves both suppression of sedimentation and agglomeration of the bright pigment and/or color pigment in a set state and good ink jettability.

However, it was found that the effect of suppressing sedimentation and agglomeration of the bright pigment by the conventional ink is not sufficient, and sedimentation, etc. may occur depending on the storage conditions. In addition, it has been found that a ball-point pen using carbon black as an ink coloring agent may cause excessive wear of the ball seat during writing, resulting in unstable ink ejection. However, the above-mentioned patent document does not describe or suggest suppression of excessive wear of the ball seats when carbon black is used as a coloring agent for the ink. There is no concept of stably forming deep and dark handwriting with a faint luster.

JP-A-11-29734

The present disclosure is an ink that uses a bright pigment and a color pigment, and is a ballpoint pen that can suppress deterioration of writability due to sedimentation and aggregation of the bright pigment and excessive wear of the ball seat due to the application of carbon black. To provide a water-based ink composition and a ball-point pen containing it.

Aspects of the present invention include:
"1. An ink composition containing a coloring pigment, a luster pigment, microcapsule particles, a shear thinning agent, and water,
Based on the total mass of the ink composition, the content of carbon black in the coloring pigment is 0 to 2.0% by mass, and the content of the luster pigment is 0.1 to 2.0% by mass. , The water-based ink composition for a ballpoint pen, wherein the content of the microcapsule particles is 1.5 to 10 times the content of the glitter pigment.
2. The colored pigment contains carbon black and an organic pigment,
The ballpoint pen according to aspect 1, wherein the content of the carbon black is 0.1 to 2.0% by mass and the content of the organic pigment is 2 to 10% by mass, based on the total mass of the ink composition. water-based ink composition.
3. The water-based ink composition for a ballpoint pen according to aspect 2, wherein the content of the organic pigment is equal to or more than 15 times the content of the carbon black, based on the total mass of the ink composition.
4. Based on the total mass of the ink composition, the relationship between the carbon black content (X), the organic pigment content (Y), and the bright pigment content (A) is 0.1. The water-based ink composition for a ballpoint pen according to aspect 2 or 3, which satisfies ≦[(X)+(A)]/(Y)≦1.
5. Based on the total weight of the ink composition, the sum of the carbon black content, the organic pigment content, the bright pigment content, and the microcapsule particle content is 5 masses. % or more and 20% by mass or less, the water-based ink composition for ballpoint pens according to any one of aspects 2 to 4.
6. The water-based ink composition for ballpoint pens according to any one of aspects 1 to 5, further comprising a polyoxyethylene polyoxypropylene alkyl ether.
7. 7. The water-based ink composition for ballpoint pens according to any one of aspects 1 to 6, wherein the color pigment comprises an organic pigment having a phthalocyanine skeleton or a dioxazine skeleton.
8. The water-based ink composition for ball-point pens according to any one of aspects 1 to 7, wherein the mass ratio of the bright pigment and the color pigment is 1:1 to 1:10.
9. The water-based ink composition for ballpoint pens according to any one of modes 6 to 8, wherein the polyoxyethylene polyoxypropylene alkyl ether has an HLB value of 10 or more and less than 15.
10. Aspects 6 to 9, wherein the content of the polyoxyethylene polyoxypropylene alkyl ether is 0.1% by mass or more and less than 4.0% by mass, based on the total mass of the ink composition. A water-based ink composition for ballpoint pens.
11. The water-based ink composition for ballpoint pens according to any one of aspects 6 to 10, wherein at least part of the polyoxyethylene polyoxypropylene alkyl ether is present on the surface of the color pigment.
12. The water-based ink composition for ballpoint pens according to any one of aspects 1 to 11, wherein the microcapsule particles encapsulate a lipophilic compound that is liquid or solid under normal temperature and normal pressure.
13. 13. The water-based ink composition for ballpoint pens according to aspect 12, wherein the lipophilic compound is one or more selected from the group consisting of aromatic hydrocarbons, esters, ketones, higher alcohols and ethers.
14. A ballpoint pen containing the water-based ballpoint pen ink composition according to any one of aspects 1 to 13.
15. A ballpoint pen refill containing the water-based ballpoint pen ink composition according to any one of aspects 1 to 13. ”.

According to an embodiment of the present invention, in an ink using a bright pigment and a color pigment, the writability is impaired due to settling and agglomeration of the bright pigment and excessive wear of the ball seat due to the application of carbon black. It is possible to provide a water-based ink composition for a ball-point pen which can be suppressed and a ball-point pen incorporating it.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail. In the present specification, "parts", "%", "ratios" and the like that indicate compounding are based on mass unless otherwise specified.
In this specification, a dark color refers to a chromatic color having both low brightness and low saturation.

A water-based ink composition for a ballpoint pen according to an embodiment of the present invention (hereinafter sometimes referred to as “aqueous ink composition”, “ink composition” or “composition”) comprises a glitter pigment and a coloring agent. A pigment, a microcapsule particle, a shear thinning agent, and water, containing carbon black that may be contained in a coloring pigment, a content of a bright pigment, and a content of the microcapsule particle and the bright pigment It is characterized in that the quantitative ratio is set within a specific range. Each component constituting the water-based ink composition according to the embodiment of the present invention will be described below.

(Luminous pigment)
The luster pigment may be any pigment that exhibits luster that reflects light in the state of handwriting. For example, the shape may be plate-like. and metal pigments such as aluminum powder.

Pigments obtained by coating a transparent base material with a metal oxide include, for example, natural mica, synthetic mica such as KMg ₃ (AlSi ₃ O ₁₀ )F ₂ , flat glass (glass flakes), silica flakes, and flakes. For example, the base material is made of a material selected from aluminum oxide, and the base material is coated with a metal oxide.
Examples of the metal oxide that coats the base material include oxides of titanium, zirconium, chromium, vanadium, iron, etc. Metal oxides containing titanium oxide as a main component are preferred. .
In addition, depending on the coating ratio of the metal oxide coating the surface of the substrate and the thickness of the coating, it exhibits a metallic luster tinged with gold, silver, yellow, red, blue or green. In addition, a metal oxide layer such as titanium oxide may be coated with iron oxide or a non-thermochromic dye/pigment.

Pigments obtained by coating a transparent base material with a metal oxide are also called pearl pigments, and specific examples thereof include the following.
Commercially available products include, for example, Iriodin 100 (silver), Iriodin 111 (silver), Iriodin 151 (silver), Iriodin 153 (silver), Iriodin 201 (gold), Iriodin 217 (red copper), Iriodin 289 (blue), 302 (gold), 504 (wine red), 530 (copper) (manufactured by Merck Japan Ltd.), Ultimica SB-100 (silver) (manufactured by Topy Industries, Ltd.), etc. . Further examples include HELICONE HCS and HELICONE HCXS (manufactured by Wacker Chemie), which are called cholesteric liquid crystal type bright pigments.

A pigment made by coating a transparent base material with a metal can be obtained, for example, by coating a glass flake with a metal by an electroless plating method or a sputtering method. Examples include glass flakes coated with silver, glass flakes coated with gold, glass flakes coated with nickel-chromium-molybdenum, and glass flakes coated with brass. glass flakes coated with a silver alloy, and glass flakes coated with titanium.

As the aluminum powder pigment, for example, aluminum flakes may be pulverized with a ball mill and polished with a petroleum solvent such as higher fatty acid or mineral spirits. Such aluminum powder pigments are fine aluminum particles on very thin scales and can be used as a paste. Commercially available aluminum powder pigments include aluminum paste WXM0630, EMERAL EMR-D5660H, EMERAL EMR-D6390, and WJC-U75C (manufactured by Toyo Aluminum Co., Ltd.).
Alternatively, thin film aluminum obtained by vacuum deposition may be finely pulverized. Commercially available products include METALURE W-52012IL, UltravarioAqua PG-24001 (manufactured by ECKART), Elgy neoSilver #500 (silver ), and Gold #500 (gold) (both of which are manufactured by Oike Kogyo Co., Ltd.). One or more kinds of luster pigments are selected and blended in the ink.

The content of the bright pigment is applied in the range of 0.1 to 2.0% by mass based on the total mass of the ink composition. A preferable content is 0.2 to 2.0% by mass, more preferably 0.5 to 2.0% by mass. With such a content, in combination with carbon black and an organic pigment, which will be described later, it is possible to obtain handwriting that is deep and dark in color, has a slight luster, and has a sense of calmness.

In the bright pigment used in the ink composition according to the embodiment of the present invention, there is no particular limitation on the particle size, but the ballpoint pen used may not be able to write, or the pigment may become an ejection groove (ink outflow hole) during writing. A particle size is selected that does not cause the possibility of clogging the ink and making it impossible to write. If the particle size is too small, it is difficult to obtain gloss in the state of handwriting. A particularly preferable average particle size is preferably in the range of 5 to 25 μm, and in order to increase the reflectance, the glitter pigment is preferably plate-like, and the aspect ratio (average particle size / average thickness) is , is preferably greater than 1, more preferably 5 or more, and even more preferably 10 or more. On the other hand, considering the dispersibility of the bright pigment, the aspect ratio is preferably 200 or less, more preferably 100 or less.
The average particle size of the bright pigment is the volume-based average particle size (median size), and can be measured, for example, using a laser particle size distribution analyzer LA-300 (volume-based) manufactured by Horiba, Ltd.

(coloring pigment)
Carbon black and organic pigments, for example, can be applied to the colored pigments of the ink composition. One type of color pigment may be contained in the ink composition according to the embodiment of the present invention, or two or more types may be used.
As the carbon black, commercially available products can be applied. Specifically, Mitsubishi carbon black #10B, #20B, #14, #25, #30, #33, #40, #44, #45, #45L, #50, #55, #95, #260, #900, #1000, #2200B, #2300, #2350, #2400B, # 2650, #2700, #4000B, CF9, MA8, MA11, MA77, MA100, MA220, MA230, MA600 and MCF88 (manufactured by Mitsubishi Chemical Corporation), Monarch 120, Monarch 700 , Monarch 800, Monarch 880, Monarch 1000, Monarch 1100, Monarch 1300, Monarch 1400, Morgal L, Legal 99R, Legal 250R, Legal 300R, Legal 330R, Legal 400R, Legal 500 and Legal 660R (manufactured by Cabot Corporation, USA), Printex A, Printex G, Printex U, Printex V, Printex 55, Printex 140U, Printex 140V, Printex 35, Printex 40, Printex 45, Printex 85, Ninepex 35 , Special Black 4, Special Black 4A, Special Black 5, Special Black 6, Special Black 100, Special Black 250, Special Black 350, Special Black 550, Color Black FW1, Color Black FW2, Color Black FW2V, Color Black FW18, Color Black FW200, Color Black S150, Color Black S160 and Color Black S170 (manufactured by Degussa Japan Co., Ltd.), Raven 5000 Ultra II, Raven 2500 Ultra, Raven 1250, Raven 760 Ultra (manufactured by Columbian Carbon Japan Co., Ltd.) can be exemplified.
A carbon black dispersion obtained by dispersing the carbon black in an aqueous solvent using a dispersant can also be applied to the carbon black described above.

The carbon black content is adjusted to 0 to 2.0% by mass based on the total mass of the ink composition. That is, even if carbon black is not included, or carbon black is included, the content is adjusted to more than 0% by mass and not more than 2.0% by mass based on the total mass of the ink composition. As a result, excessive wear of the ball seat can be suppressed, so that the ink ejection property is not impaired. In consideration of suppressing wear of the ball seat while forming dark handwriting, the content of carbon black is preferably 0.1 to 2.0% by mass, more preferably 0.2 to 1.5% by mass. %, more preferably 0.3 to 1.2% by mass.

Conventionally known organic pigments can be applied, including azo pigments, indigo pigments, phthalocyanine pigments, quinacridone pigments, thioindigo pigments, threne pigments, perinone pigments, perylene pigments, phthalone pigments, and dioxane pigments. pigments, isoindolinone-based pigments, metal complex-based pigments, methine/azomethine-based pigments, diketopyrrolopyrrole-based pigments, and the like. Similar to carbon black, organic pigment dispersions obtained by dispersing an organic pigment in a water-based solvent can also be applied to such an organic pigment. I. Pigment Blue 15:3B [product name: S.I. S. Blue GLL, pigment content 22%, manufactured by Sanyo Pigment Co., Ltd.], C.I. I. Pigment Red 146 [product name: S.I. S. Pink FBL, pigment content 21.5%, manufactured by Sanyo Color Co., Ltd.], C.I. I. Pigment Yellow 81 [product name: TC Yellow FG, about 30% pigment content, manufactured by Dainichiseika Kogyo Co., Ltd.], C.I. I. Pigment Red 220/166 [product name: TC Red FG, about 35% pigment content, manufactured by Dainichiseika Kogyo Co., Ltd.] and the like.
In an embodiment of the invention, the color pigment may contain an organic pigment having a phthalocyanine skeleton or a dioxazine skeleton. The pigment has strong coloring power and light fastness, and is an extremely excellent coloring pigment. However, as a result of investigations by the present inventors, it was found that the pigment tends to separate in the ink. Furthermore, the present inventors have found that by containing a polyoxyethylene polyoxypropylene alkyl ether described later, even if the pigment is contained, separation of the pigment can be sufficiently suppressed, and good ink stability and the like can be obtained. I found that I can get
Examples of organic pigments having a phthalocyanine skeleton include Pigment Blue 15, Pigment 15:1, Pigment 15:2, Pigment 15:3, Pigment 15:4, Pigment 15:6, Pigment 16, Pigment 17:1, Pigment Green 7, 36, 58 and the like.
Examples of organic pigments having a dioxazine skeleton include Pigment Violet 23 and 37.

The content of the organic pigment is preferably in the range of 2 to 10% by mass based on the total mass of the ink composition, in order to adjust the color tone of the handwriting to be deep and dark when used in combination with carbon black. A more preferable content is 3 to 8% by mass, more preferably 4 to 6% by mass.

In consideration of adjusting the color tone of the handwriting to a dark and dark color, the content of the organic pigment should be equal to or more than 15 times the content of carbon black, based on the total mass of the ink composition. , more preferably 1 to 13 times, and even more preferably 1.5 to 12 times.

In addition, considering that the color tone of the handwriting is dark and dark and the handwriting has a faint gloss, the content of carbon black (X), the content of organic pigment (Y), and the content of bright pigment The relationship with (A) preferably satisfies 0.1 ≤ [(X) + (A)] / (Y) ≤ 1, and 0.2 ≤ [(X) + (A)] / (Y) ≤0.9 is more preferable, and 0.25≤[(X)+(A)]/(Y)≤0.85 is even more preferable.

In an embodiment of the present invention, the mass ratio of the luster pigment and the color pigment is preferably 1:1 to 1:10, more preferably 1:3 to 1:10. This makes it possible to obtain better ink jettability and writing feeling.

(microcapsule particles)
Microcapsule particles (hereinafter sometimes simply referred to as "MC particles") have the effect of suppressing adsorption between bright pigments and/or adsorption between coloring pigments, effectively suppressing aggregation of pigments. can.

Microcapsule particles are obtained by encapsulating the dispersion in a shell made of a wall film-forming substance by a conventionally known microencapsulation method. Gum, rosin, rosin ester, ethyl cellulose, carboxymethyl cellulose, paraffin, tristearin, polyvinyl alcohol, polyethylene, polypropylene, acrylic resin, vinyl resin, polyisobutene, polyurethane, polybutadiene, polyester, polyamide, epoxy resin, phenolic resin, silicone resin , polystyrene, melamine resin, etc. can be used singly or in combination.
Examples of the microencapsulation method include an interfacial polymerization method, an interfacial polycondensation method, an in situ polymerization method, a coacervation method, an in-liquid curing coating method, a phase separation method from an aqueous solution, a phase separation method from an organic solvent, and a melting method. A dispersion cooling method, an air suspension coating method, a spray lining method, and the like can be mentioned, and can be selected as appropriate.

Microcapsule particles may have inclusions.
Examples of inclusions include substances that are liquid or solid under normal temperature and normal pressure, and an example thereof is a lipophilic compound. The lipophilic compound is, for example, one or more selected from the group consisting of aromatic hydrocarbons, esters, ketones, higher alcohols and ethers. Substances described in paragraphs [0026] to [0035] of JP-77260 can be mentioned. Furthermore, as the lipophilic compound, for example, an electron-donating color-developing organic compound ((a) component) described in paragraphs [0036] to [0037] of JP-A-2021-31679, [0038] to [0050] and the electron-accepting compound ((b) component) described in paragraph [0058] of JP-A-2020-196857, alcohols described in paragraphs [0051] to [0070] of JP-A-2021-31679, Thermochromic compositions comprising substances such as esters, ketones, ethers, and amides (component (c)), the components (a), (b) and (c) can also be exemplified. Furthermore, the photochromic material described in paragraph [0073] of JP-A-2021-31679 and the photochromic composition described in paragraphs [0074] to [0075] of the same can also be applied as the lipophilic compound. By using a lipophilic compound having a specific gravity of 1.0 or less, the specific gravity of the MC particles can be reduced to easily adjust the specific gravity difference between the ink composition and the medium. It becomes easier to maintain the dispersed state inside.
In this specification, normal temperature and normal pressure refer to 20° C. and 1.01325×10 ⁵ Pa.

The microcapsule particles can be microencapsulated to have an average particle size in the range of 0.2-5 μm, preferably 0.5-3 μm. By setting the average particle diameter to 0.2 μm or more, aggregation of the bright pigment can be effectively suppressed with a small amount. Further, by setting the average particle diameter to 5 μm or less, it is possible to suppress the deterioration of the dischargeability of the MC particles. As the average particle diameter of the microcapsules, the average particle diameter (median diameter) of particles equivalent to a sphere of equal volume is used. The optimum measurement can be performed using a laser diffraction/scattering particle size distribution measuring apparatus LA-300 manufactured by Horiba, Ltd., which is calibrated by a direct measurement method. As a direct measurement method used for calibration,
(i) an image analysis method in which the equivalent diameter is measured by measuring the area (two-dimensional) of individual particles from images taken with a microscope; or (ii) a microscopic aperture in the detector using a Coulter counter. Coulter method (Electrical detection band method), which measures the equivalent diameter from the change in impedance that occurs when particles pass through the hole when a constant current is passed through the hole
etc., and the calibration of the laser measurement method is performed based on the values obtained by these.
The average particle size is measured by image analysis, for example, the area of particles is determined using image analysis type particle size distribution measurement software "Macview" manufactured by Mountec, Inc., and the projected area circle equivalent diameter ( Heywood diameter) can be calculated, and the average particle diameter of particles equivalent to a sphere of equal volume can be measured.
The measurement of the average particle size by the Coulter method is applicable when the particle size of all particles or most of the particles exceeds 0.2 μm. 4e" can be used.

The content of the microcapsule particles in the ink composition is 1.5 times or more and 10 times or less on a mass basis with respect to the content of the luster pigment. When the content of the microcapsule particles is applied within the above range, the sedimentation and agglomeration of the bright pigment can be suppressed, and the ink jettability and writing feeling can be improved. If the content of the microcapsule particles is less than 1.5 times the content of the bright pigment, the effect of suppressing sedimentation and aggregation of the bright pigment is insufficient, and the content of the microcapsule particles is 10 times. If it exceeds , the ink jettability is lowered and the handwriting tends to be blurred. The content of the microcapsule pigment is preferably 2 to 8 times, more preferably 2.5 to 6 times, and still more preferably 3 to 5 times that of the luster pigment.

(Shear thinning agent)
Water-soluble or dispersible substances are effective as shear-thinning agents, such as xanthan gum, welan gum, zeta-sea gum, diutan gum, macrohomopsis gum, and organic acid-modified heteropolysaccharides whose constituent monosaccharides are glucose and galactose. Polymers with a molecular weight of 100,000 to 150,000 mainly composed of succinoglycan (average molecular weight of about 100,000 to 8,000,000), guar gum, locust bean gum and derivatives thereof, alginic acid alkyl esters, methacrylic acid alkyl esters, Glucomannan, carrageenan and other carbohydrates with gelling ability extracted from seaweed, poly N-vinyl-carboxylic acid amide cross-linked product, benzylidene sorbitol and benzylidene xylitol or derivatives thereof, cross-linkable acrylic acid polymer, inorganic fine particles, HLB Examples include nonionic surfactants having a value of 8 to 12, metal salts and amine salts of dialkylsulfosuccinic acid, and the like. Furthermore, an N-alkyl-2-pyrrolidone and an anionic surfactant may be added in combination to the ink composition. Among the above, xanthan gum and succinoglycan are preferably used because high shear thinning properties can be obtained, and it is easy to achieve both suppression of sedimentation and aggregation of pigments and microcapsule particles during standing and good ink ejection properties during writing. be done.

The content of the shear thinning agent is preferably 0.1 to 0.5% by mass, more preferably 0.2 to 0.5% by mass, more preferably 0.2 to 0.5% by mass, based on the total mass of the ink composition. More preferably 25 to 0.45% by mass. When the content is within this range, sedimentation and agglomeration of the pigment and microcapsule particles during standing can be suppressed, good ink jettability can be ensured during writing, and bleeding of handwriting can be easily suppressed.

An ink composition according to an embodiment of the present invention contains a bright pigment, a coloring pigment, microcapsule particles, and water while applying a shear thinning agent, carbon black that can be contained in the coloring pigment, and By adjusting the content of the luster pigment and the content ratio of the microcapsule particles and the luster pigment within a predetermined range, sedimentation and agglomeration of the luster pigment, and excessive ball seat accompanying the application of carbon black Impairment of writability due to abrasion can be suppressed. Furthermore, by containing predetermined amounts of carbon black and an organic pigment as coloring pigments, it is possible to stably obtain handwriting that is deep and dark in color, tinged with a faint luster, and has a sense of calmness.
The ink composition, based on the total mass of the ink composition, contains a bright pigment content (A), a carbon black content (X), an organic pigment content (Y), and microcapsules The total content of the particles (B) is preferably 5% by mass or more and 20% by mass or less. By setting the total content in the above range, it is possible to form a calm handwriting, and the ink composition To improve the dry-up resistance of an object, and to suppress the impossibility of rewriting due to drying of the pen tip even when a ball-point pen containing an ink composition is stored with the pen tip exposed.
A more preferable range of the sum of (A), (X), (Y), and (B) is 6% by mass or more and 15% by mass or less, and a more preferable range is 7% by mass or more and 13% by mass or less. .

The ink composition may optionally contain a dye soluble in an aqueous medium, a fluorescent pigment, a metal oxide pigment such as titanium oxide and zinc oxide, a pigment dispersant, a water-soluble organic solvent, a lubricant, a pH adjuster, and an antirust agent. agents, preservatives or antifungal agents, wetting agents, antifoaming agents, foam suppressing agents, penetrating agents, dextrin, etc. can be applied.

As the dye, acid dyes, basic dyes, direct dyes, etc. can be used. Acid dyes include new coccine (CI 16255), tartrazine (CI 19140), acid blue black 10B (CI 20470), Guinea Green (CI 42085), Brilliant Blue FCF (CI 42090), Acid Violet 6B (CI 42640), Soluble Blue (CI 42755) ), naphthalene green (CI 44025), eosin (CI 45380), phloxine (CI 45410), erythrosine (CI 45430), nigrosine (CI 50420), acid flavin (C.I.56205) and the like are used.
Basic dyes include chrysoidine (CI 11270), methyl violet FN (CI 42535), crystal violet (CI 42555), malachite green (CI 42000), Victoria Blue FB ( CI 44045), rhodamine B (CI 45170), acridine orange NS (CI 46005), methylene blue B (CI 52015) and the like are used.
Direct dyes include Congo Red (CI 22120), Direct Sky Blue 5B (CI 24400), Violet BB (CI 27905), Direct Deep Black EX (CI 30235), Kaya Las Black G Conch (CI 35225), Direct Fast Black G (CI 35255), Phthalocyanine Blue (CI 74180) and the like are used.

As the fluorescent pigment, a fluorescent pigment in the form of synthetic resin fine particles obtained by making a solid solution of various fluorescent dyes in a resin matrix can be used.
As the pigment dispersant, water-soluble resins, water-soluble polymers, surfactants and the like can be applied.
The ink composition according to the embodiment of the present invention preferably contains a specific surfactant such as polyoxyethylene polyoxypropylene alkyl ether in addition to microcapsule particles and the like. This makes it easier to suppress the separation of the color pigment without reducing the shear thinning effect. At least part of the polyoxyethylene polyoxypropylene alkyl ether may be present on the surface of the colored pigment.
Polyoxyethylene polyoxypropylene alkyl ether can be generally represented by the following formula (1).

H—O—(C ₂ H ₄ O) _m (C ₃ H ₆ O) _n —R ₁ (1)

In the above formula (1), R ₁ is an aliphatic hydrocarbon group and may have 4 to 24 carbon atoms, m is the average number of moles of ethylene oxide added and may be 3 to 45, and n is propylene. The average number of moles of oxide added can be a number from 1 to 33.
Examples of commercially available polyoxyethylene polyoxypropylene alkyl ethers include Newpol 50HB series manufactured by Sanyo Chemical Industries, Ltd., Adekanol BPE series manufactured by ADEKA Corporation, NIKKOL PBC series manufactured by Nikko Chemicals Co., Ltd., and Nippon Emulsion Co., Ltd. ), Braunon DC series, Braunon SRP series, and Fine Surf NDB series produced by Aoki Yushi Kogyo Co., Ltd. One type or two or more types of polyoxyethylene polyoxypropylene alkyl ethers may be contained in the ink composition for a ballpoint pen according to the embodiment of the present invention.

The HLB value of the polyoxyethylene polyoxypropylene alkyl ether is preferably 10 or more and less than 15. This makes it possible to obtain better ink ejection properties. The HLB value is a numerical value representing the balance between hydrophobicity and hydrophilicity of a dispersant or the like. In general, a higher HLB value indicates a higher hydrophilicity, and a lower HLB value indicates a higher hydrophobicity. In the embodiment of the present invention, the HLB value is determined by Griffin's method, and specifically, it is determined by the following formula (2).

HLB value = 20 x (sum of formula weights of hydrophilic moieties)/(molecular weight) (2)

The content of polyoxyethylene polyoxypropylene alkyl ether is preferably 0.1% by mass or more and less than 4.0% by mass based on the total mass of the ink composition. It is more preferably 0.5% by mass or more and less than 4.0% by mass, and more preferably 0.5% by mass or more and 3.5% by mass or less. Thereby, a better writing feeling can be obtained.

As the water-soluble organic solvent, conventional general-purpose solvents can be used, such as ethanol, propanol, butanol, glycerin, ethylene glycol, diethylene glycol, thiodiethylene glycol, hexylene glycol, 1,3-butanediol, neoprene glycol, and polyethylene glycol. , propylene glycol, butylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, propylene glycol monoethyl ether, 2-pyrrolidone, N- and methyl-2-pyrrolidone.
The water-soluble organic solvent is applied in an amount of, for example, 1 to 40% by mass, preferably 5 to 30% by mass, based on the total mass of the ink composition, and one kind or two or more kinds can be used.

Lubricants include phosphate ester surfactants, metal soaps, polyalkylene glycol fatty acid esters, ethylene oxide addition type cationic surfactants, N-acyl amino acid surfactants, dicarboxylic acid type surfactants, β-alanine type surfactants. Surfactants, 2,5-dimercapto-1,3,4-thiadiazole and its salts or oligomers, 3-amino-5-mercapto-1,2,4-triazole, thiocarbamate, dimethyldithiocarbamate, α -lipoic acid, condensates of N-acyl-L-glutamic acid and L-lysine, salts thereof, and the like, and phosphate surfactants are preferably applicable.

Conventionally known acidic substances and basic substances can be applied to the pH adjuster. Examples of acidic substances include hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, carbonic acid, boric acid, lactic acid, citric acid, tartaric acid, and malic acid. Examples of basic substances include strong alkalis such as sodium hydroxide and potassium hydroxide, and weak alkalis such as ammonia, sodium carbonate, sodium hydrogen phosphate and potassium hydrogen phosphate. Alkanolamines such as monoethanolamine, diethanolamine and triethanolamine are also applicable as the basic substance. The basic substance described above can also be applied as a neutralizing agent for a phosphate surfactant.

Examples of antirust agents include benzotriazole and its derivatives, tolyltriazole, dicyclohexylammonium nitrite, diisopropylammonium nitrite, sodium thiosulfate, saponin, and dialkylthiourea. -methyl-4-isothiazolin-3-one, 1,2-benzisothiazolin-3-one, 2-n-octyl-4-isothiazolin-3-one, 2-methyl-4,5-trimethylene-4-isothiazolin- 3-one, N-(n-butyl)-1,2-benzisothiazolin-3-one, 2-pyridinethiol-1-oxide sodium, 3-iodo-2-propynylbutyl carbamate, benzotriazole and phenol, benzoic acid sodium, sodium dehydroacetate, potassium sorbate, propyl paraoxybenzoate, 2,3,5,6-tetrachloro-4-(methylsulfonyl)pyridine, and wetting agents such as urea, sorbitol, mannitol, sugar, glucose, reduced starch hydrolysate, sodium pyrophosphate and the like.

Furthermore, as air-absorbing agents, for example, ascorbic acids, erythorbic acids, α-tocopherol, catechins, synthetic polyphenols, kojic acid, alkyl hydroxylamines, oxime derivatives, α-glucosylrutin, α-lipoic acid, phosphonates, phosphines acid salts, sulfites, sulfoxylates, dithionites, thiosulfates, thiourea dioxide, and the like.

The dextrin is preferably a sugar mixture containing starch saccharification products with 8 or more sugars and/or reduced products thereof. The saccharide mixture preferably contains 30% by mass or more, more preferably 50% by mass or more, and particularly preferably 70% by mass or more of starch saccharified products having 8 or more sugars. Such a dextrin is preferable because it has excellent film-forming properties, and has a large effect of suppressing the evaporation of water from the pen tip, thereby suppressing the dry-up of the pen tip.

The ink composition also contains N-vinyl-2-pyrrolidone oligomer, N-vinyl-2-piperidone oligomer, N-vinyl-ε-caprolactam oligomer, N-vinyl-2-pyrrolidone, N-cyclohexyl Addition of anti-thickening agents such as -2-pyrrolidone, ε-caprolactam, etc., can also enhance the functionality in the hive-and-recess form. One or two or more water-soluble resins such as alkyd resins, acrylic resins, styrene-maleic acid copolymers, polyvinylpyrrolidone, polyvinyl alcohol, dextrin, etc. may be added as long as the drying resistance is not impaired. Furthermore, a water-soluble resin may be added to impart adhesion and viscosity to the paper surface. Examples of the water-soluble resin include alkyd resins, styrene-maleic acid copolymers, cellulose derivatives, polyvinylpyrrolidone, polyvinyl alcohol, and dextrin.

The ink composition preferably has a viscosity of 600 to 2000 mPa·s measured at a shear rate of 3.84 sec ⁻¹ and a viscosity of 20 to 100 mPa·s measured at a shear rate of 384 sec ⁻¹ . More preferably, the ink composition has a viscosity of 1000 to 1600 mPa·s measured at a shear rate of 3.84 sec ⁻¹ and a viscosity of 30 to 60 mPa·s measured at a shear rate of 384 sec ⁻¹ . When the viscosity of the ink composition is within the above range, leakage of ink from the tip of the ballpoint pen in a stationary state and sedimentation and aggregation of the pigment are sufficiently suppressed, and the ink ejectability from the tip of the ballpoint pen during writing is good. , making it easy to form clear handwriting. The viscosity of the ink composition can be adjusted to a desired range by appropriately adjusting the ink composition, such as the contents of the bright pigment, color pigment, microcapsule particles, and shear thinning agent.
The viscosity is measured with the ink composition at 20° C., and a rheometer “Discovery HR-2” manufactured by TA Instruments Co., Ltd. can be used as the measuring device.

(Ballpoint pen and ballpoint refill)
A ballpoint pen, for example, has an ink storage tube filled with an ink composition in a barrel, the ink storage tube communicates with a ballpoint pen tip having a ball attached to the tip, and is further stored in the ink storage tube. A structure in which a liquid plug for preventing backflow is in close contact with the end face of the ink composition can be exemplified.
The tip of the ballpoint pen, which serves as the writing tip, is, for example, machined from metal to form a ball receiving seat and an ink outlet inside, or a metal pipe with a plurality of inward projections on the inner surface near the tip. It is possible to apply an ink outflow gap which is formed by press deformation and which extends radially outward in the radial direction from the central portion between the inwardly protruding portions. The contact area is relatively small, and a smooth writing feeling can be given with a low writing pressure.
For example, the metal pipe has a straight cylindrical body (straight tube-shaped cylindrical body) at the tip, and has a configuration in which the outer diameter and the inner diameter are enlarged behind the tip. The shape of the pipe may be a straight cylindrical body as a whole.

The ball held in the ballpoint pen tip is made of cemented carbide, stainless steel, ruby, ceramic, etc., and has an outer diameter of 0.1 to 2.0 mm, preferably 0.2 to 1.2 mm, more preferably 0.28 to 0.28 mm. A 0.7 mm ball is effective. When using a ball of 0.7 mm or less, for the purpose of increasing the ink ejection amount and/or for the purpose of stably ejecting microcapsule particles (especially 0.1 μm or more) having a particle diameter larger than that of ordinary coloring pigments, the tip clearance is is required to be large, the ink remaining on the tip is likely to evaporate. Therefore, the ink of the embodiment of the present invention acts more effectively.
In the ballpoint pen tip, an elastic member is arranged in the tip to spring the rear end of the ball forward, and when writing is not performed, the ball is pressed against the inner edge of the tip of the tip so as to be in a close contact state, and when writing, the pen pressure is applied. The ball can be retracted to allow the ink to flow out, thereby suppressing ink leakage when not in use.
Examples of the resilient member include a thin metal wire spring, a spring having a straight portion (rod portion) at one end, a linear plastic processed body, etc., which can be pressed with a resilient force of 5 to 40 g. applied as

For the ink storage tube that stores the ink composition, for example, a molding made of a thermoplastic resin such as polyethylene, polypropylene, polyethylene terephthalate, or nylon, or a metal tubular body is used. In addition to directly connecting the tip to the ink containing tube, the ink containing tube and the tip may be connected via a connection member (tip holder).

The ball-point pen may have an ink storage tube in the form of a ball-point pen refill, and the ball-point pen refill may be stored in a barrel made of resin, metal, or the like, or the barrel itself with the ball-point pen body attached to the tip portion may be used as the ink reservoir. Alternatively, ink may be filled directly into the barrel.

When the ink storage tube is in the form of a ballpoint pen refill, the ballpoint pen refill includes the ink storage tube that stores the ink composition and the ballpoint pen body that is attached to the ink storage tube directly or via a connecting member and holds the ball rotatably. and

When the ink composition is applied to a retractable ballpoint pen, the structure and shape of the retractable ballpoint pen are not particularly limited. Any structure can be used as long as it has a structure in which the tip of the writing tip protrudes from the opening of the barrel by the operation of the retraction mechanism. Methods of operating the retractable mechanism include, for example, a knock type, a rotating type, a sliding type, and the like. The knock type has a structure in which a knock portion is provided at the rear end portion of the barrel or on the side surface of the barrel, and the tip portion of the writing is protruded and retracted from the front end opening portion of the barrel by pressing of the knock portion, or a clip portion provided on the barrel. can be exemplified as a configuration in which the writing tip portion is protruded and retracted from the front end opening of the barrel by pressing . As a rotary type, there is provided a rotating portion at the rear portion of the barrel, and by rotating the rotating portion, the writing tip portion can appear and disappear from the opening at the front end of the barrel. As for the slide type, there is a slide portion on the side surface of the barrel, and the tip of the writing part is moved in and out from the front end opening of the barrel by operating the slide, or by sliding the clip portion provided on the barrel, A configuration in which the writing tip portion protrudes and retracts from the front end opening of the barrel can be exemplified. The retractable ballpoint pen is a composite type retractable ballpoint pen in which a plurality of ballpoint pen refills are accommodated in a barrel, and the writing tip of one of the ballpoint pen refills is retracted from the front end opening of the barrel by the operation of the retractable mechanism. good too.

The rear end of the ink composition contained in the ink containing tube is filled with an ink backflow preventer. The ink backflow preventer can consist of a non-volatile liquid or a low-volatility liquid. Specifically, petrolatum, spindle oil, castor oil, olive oil, refined mineral oil, liquid paraffin, polybutene, α-olefin, α-olefin oligomer or co-oligomer, dimethyl silicone oil, methylphenyl silicone oil, amino-modified silicone oil, Polyether-modified silicone oil, fatty acid-modified silicone oil, and the like can be mentioned, and one kind can be used alone or two or more kinds can be used in combination. At least one of the non-volatile liquid and the hardly volatile liquid is preferably thickened to a suitable viscosity by adding a thickening agent. As a thickener, silica whose surface is hydrophobically treated, fine particle silica whose surface is methylated, aluminum silicate, swelling mica, bentonite with hydrophobic treatment, clay-based thickeners such as montmorillonite, magnesium stearate, calcium stearate , fatty acid metal soaps such as aluminum stearate and zinc stearate, tribenzylidene sorbitol, fatty acid amides, amide-modified polyethylene waxes, hydrogenated castor oil, dextrin compounds such as fatty acid dextrin, and cellulose compounds. Furthermore, a liquid ink backflow prevention member and a solid ink backflow prevention member can be used together.

The form of the ball-point pen is not limited to the one described above, and it may be a double-headed writing instrument in which pen bodies of different forms are attached or pen bodies that lead out ink compositions of different colors are attached.

Furthermore, a friction member for erasing or discoloring handwriting by frictional heat can be used together with the ballpoint pen.
As the friction member, an elastic body such as an elastomer, a plastic foam, or the like, which is rich in elasticity and capable of generating moderate friction during friction and generating frictional heat, is suitable. An eraser can also be used to rub the handwriting, but since eraser shavings are generated during rubbing, the aforementioned friction member is preferably used.
Examples of materials for the friction member include styrene thermoplastic elastomers such as silicone resin, SEBS resin (styrene ethylene butadiene styrene block copolymer), SBS resin (styrene butylene styrene copolymer), polyester resin, polypropylene resin and styrene. A mixture of a thermoplastic elastomer, a mixture of a polypropylene resin and a thermoplastic polypropylene elastomer, and the like are used.
The friction member can be a combination of a ballpoint pen and a separate member of arbitrary shape (friction body) to obtain a writing instrument set.
In the case of a cap-type ballpoint pen, the place where the friction member is provided is not particularly limited. The friction member itself can be formed of a friction member, or the friction member can be provided at the tip end (top) of the cap or the rear end of the barrel (the portion where the writing tip is not provided).
In the case of a retractable ballpoint pen, the place where the friction member is provided is not particularly limited. A friction member can be provided in the vicinity of the opening of the barrel, the rear end of the barrel (the portion where the writing tip is not provided), or the knock portion.

Examples will be described below, but the embodiments of the present invention are not limited to these examples.

Table 1 shows the compositions of the glitter inks for ball-point pens of Examples, and Table 2 shows the compositions of the glitter inks for ball-point pens of Comparative Examples. In addition, the numerical value of the composition in a table|surface shows a mass part.
The average particle size of the bright pigment is measured using a laser particle size distribution analyzer LA-300 (volume basis) manufactured by Horiba, Ltd., and the median diameter is taken as the average particle size.

In addition, the average particle diameter (median diameter) based on volume is used as the average particle diameter of the microcapsule pigment. method (electrical detection zone method) particle size measuring device, laser diffraction/scattering type particle size distribution measuring device (device name: LA-300, manufactured by HORIBA, Ltd.), and the like can be used.
When a laser diffraction/scattering particle size distribution analyzer is used, the measurement is performed using a measuring instrument calibrated with a standard sample or another measuring instrument such as the Coulter method (electrical detection zone method).
If there is a difference in the numerical values obtained depending on the measuring instrument, the numerical values obtained using the image analysis type particle size distribution measurement software are given priority.
In this example, the laser diffraction particle size distribution measuring device (device name: LA-300, manufactured by Horiba, Ltd.) calibrated by the Coulter method (electrical detection zone method) was used to measure the average particles by volume. Diameter (median size) and particle size were measured.

The content of raw materials in the table will be explained along with the note numbers.
(1) Aluminum powder pigment, manufactured by Toyo Aluminum Co., Ltd., trade name: Aluminum paste EMERAL EMR-D5660H (average particle size: 9 μm, active ingredient: 60% by mass) (2) Stearyl stearate using an interfacial polymerization method Encapsulated microcapsule particles (average particle size: 2 μm, wall film-forming substance: urethane resin)
(3) Microcapsule particles encapsulating stearyl stearate using an in situ polymerization method (average particle size: 2 μm, wall film-forming material: melamine resin)
(4) Acid Blue 90
(5) 40% by mass aqueous solution of block copolymer (trade name: DISPER BYK-190, manufactured by BYK)
(6) Polyoxyethylene aryl ether phosphate (trade name: Plysurf AL, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)
(7) Succinoglycan (trade name: Leozan, manufactured by Sansho)
(8) Trade name: Sundec #100 (sugar mixture containing starch saccharification products with 8 or more sugars, manufactured by Sanwa Denpun Kogyo Co., Ltd.)

Preparation of ink Add ingredients other than the shear thinning agent to water, stir at 20°C with a disper at 2000 rpm for 1 hour, then add succinoglycan as a shear thinning agent and stir for an additional hour. Each ink composition was thus prepared.

Preparation of Ink Backflow Preventer To 98.5 parts of polybutene as a base oil, 1.5 parts of a fatty acid amide as a thickening agent was added, followed by kneading with a triple roll to obtain an ink backflow preventer.

Preparation of ballpoint pen 1.0 g of the above ink composition for ballpoint pen was filled in a refill for a ballpoint pen (trade name: Friction Point Clicker 05, manufactured by Pilot Corporation), and the above ink backflow preventer was attached to the rear end of the ink composition. , the ball-point pen refill was incorporated into the ball-point pen outer shaft to prepare a sample ball-point pen. The ball-point pen refill has a stainless steel ball-point pen tip fitted to one end of the ink storage tube. A plurality of inward projections are provided on the inner surface near the tip of a metal pipe whose inner diameter expands by pressing deformation from the outer surface, and between the inward projections, radial direction from the center part A ball holding chamber having an ink outflow gap extending radially outward is provided, and a cemented carbide ball having a diameter of 0.5 mm is held in the ball holding chamber.

The following evaluations were performed using the sample ball-point pens and ink compositions.
As the test paper for writing, trade name: Copy Paper Standard Type II Super High White, sold by Kaunet Co., Ltd. was used.

Evaluation of Color Tone and Glossiness A 10 mm-square square was painted on the test paper with the ballpoint pen, and the color tone and brightness of the handwriting were visually observed.

-Writability Evaluation A spiral circle was written on the test paper at a speed of 4 m/min with the above ballpoint pen, and the handwriting was visually confirmed. As for the evaluation criteria, A and B were accepted.
A: Writing is possible until the ink is completely consumed without the handwriting being blurred.
B: Writing is slightly blurred, but writing is possible until the ink is completely consumed.
C: Significant blurring of handwriting occurred, and writing became impossible before the ink was completely consumed.

Evaluation of Rewritability Each ballpoint pen containing the ink compositions of Examples 1 to 11 was placed horizontally and allowed to stand at 25° C. for 60 days. The ballpoint pen was returned to room temperature after it had been allowed to stand still, and 12 circles per line were spirally written over two lines on the test paper, and the handwriting was visually observed. As for the evaluation criteria, A and B were accepted.
A: It is possible to form a handwriting without blurring from the first stroke to the end of writing.
B: Blurring is visually recognized in one or two circles.
C: Impossible to write or fading can be confirmed in three or more circles.
The results of each evaluation are shown in Tables 1 and 2.

The ink compositions for ballpoint pens shown in Table 3 below were prepared. In addition, the numerical value of the composition in a table|surface shows a mass part. The average particle size of the bright pigment is measured using a laser particle size distribution analyzer LA-300 (volume basis) manufactured by Horiba, Ltd., and refers to the median size. In addition, the average particle size (volume basis) of the microcapsule pigment (MC particles) was measured by a laser diffraction/scattering particle size distribution measuring device (device name: LA-300, manufactured by HORIBA, Ltd.) calibrated by the image analysis method. ) and refers to the median diameter.

The contents of the raw materials in Table 3 above will be explained along with the note numbers.
(1) Aluminum powder pigment: manufactured by Toyo Aluminum Co., Ltd., trade name: aluminum paste EMERAL EMR-D6390 (average particle size: 7 μm, active ingredient: 55% by mass)
(2) Pearl pigment: Merck Japan, trade name: Iriodin 221 (average particle size: 15 μm)
(3) MC Particles 1: microcapsule particles encapsulating stearyl stearate using an interfacial polymerization method (average particle diameter: 2 μm, wall film-forming substance: urethane resin)
(4) MC Particles 2: microcapsule particles encapsulating stearyl stearate using an in situ polymerization method (average particle size: 2 μm, wall-forming material: melamine resin)
(5) Polyoxyethylene polyoxypropylene alkyl ether (HLB: 10.5) ... INCI name: PPG4-ceteth-10
(6) Polyoxyethylene polyoxypropylene alkyl ether (HLB: 13)... INCI name: PPG6-decyltetradeceth-30
(7) Polyoxyethylene polyoxypropylene alkyl ether (HLB: 15) ... INCI name: PPG2-deceth-30
(8) Sulfosuccinic acid-based surfactant: manufactured by Kao Corporation, trade name: Pelex OT-P (active ingredient: 70% by mass)
(9) Polyoxyethylene alkyl sulfate: manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name: Hitenol NF-13 (active ingredient: 95% by mass)
(10) Polyoxyethylene styrenated phenyl ether: Daiichi Kogyo Seiyaku Co., Ltd., trade name: Noigen EA-137 (HLB: 13)
(11) Polyvinylpyrrolidone: manufactured by BASF, trade name: Sokalan K 17 P
(12) Water... ion-exchanged water (13) Others... solvent: glycerin,
Lubricant: Polyoxyethylene aryl ether phosphate (trade name: Plysurf AL, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)
Dextrin (sugar mixture of saccharified starch with 8 or more sugars): trade name Sundec 100, manufactured by Sanwa Denpun Kogyo Co., Ltd.,
Neutralizing agent: triethanolamine, and preservative: 1,2-benzisothiazolin-3-one (trade name: Proxel XL-2, manufactured by Lonza Japan Co., Ltd.)

Preparation of ballpoint pen ink composition Components other than the shear thinning agent were added to water, and after stirring at 20°C with a disper at 2000 rpm for 1 hour, succinoglycan or xanthan gum was added as a shear thinning agent. Each ink composition was prepared by further stirring for 1 hour.

Preparation of Ink Backflow Preventer To 98.5 parts by mass of polybutene as base oil, 1.5 parts by mass of fatty acid amide as a thickening agent was added, followed by kneading with a triple roll to obtain an ink backflow preventer.

The following evaluations were performed using the above sample ballpoint pens and ink compositions.

[Color tone evaluation and glitter evaluation]
A test paper (trade name: Copy Paper Standard Type II Super High Whiteness, sold by Kaunet Co., Ltd.) was filled with a square of 10 mm square with the above ballpoint pen, and the color tone and the degree of brilliance of the handwriting were visually observed.

[Evaluation of writing performance (evaluation of ink ejection performance, evaluation of presence or absence of abnormal handwriting)]
A spiral circle was written on the test paper at a speed of 4 m/min until the ink was completely consumed, and the handwriting was visually confirmed. As the test paper, the same kind of paper as the test paper used in the evaluation of [color tone evaluation] and [gloss evaluation] was used. As for the evaluation criteria, A and B were accepted.
A: There are no linear ink non-adherence portions (line cracks in handwriting) or adhesion of ink droplets (bottom) in the handwriting.
B: A line crack with a length of 5 cm or less or a bulge at one point is observed in the handwriting.
C: Line cracks exceeding 5 cm in length or bulges at two or more locations are observed in the handwriting.

Table 4 shows the evaluation results of the ballpoint pen ink compositions of Examples 12 to 26 and Reference Examples 1 to 3.

The ink compositions for ballpoint pens of Examples 12 to 26 and Reference Examples 1 to 3 were further evaluated as follows.

[Ink stability evaluation (handwriting gradation evaluation)]
A plurality of ball-point pens containing the same type of ink were allowed to stand at 50° C. for 30 days. At that time, some of the ball-point pens were allowed to stand with their tip ends facing upward, and the remaining ball-point pen tips were left standing with their tip ends facing downward.
The ballpoint pen was returned to room temperature after it had been allowed to stand still, and 12 circles per line were spirally written over two lines on the test paper, and the density of the handwriting was visually observed. As the test paper, the same kind of paper as that used in [Evaluation of Color Tone and Evaluation of Glitter] was used. The evaluation criteria were as follows.
A: Regardless of the orientation of the ball-point pen tip when left stationary, a handwriting with the same density is formed from the first stroke to the end of writing.
B: The handwriting formed with the ball-point pen with the ball-point pen tip facing downward is darker at the time of the first writing than the handwriting formed with the ball-point pen with the ball-point pen tip facing upward. By the time 1-2 circles are formed from the brush, the density of the handwriting is about the same.
C: The handwriting formed with a ballpoint pen left standing with the ballpoint pen tip facing down forms two circles from the first stroke compared to the handwriting formed with a ballpoint pen standing still with the ballpoint pen tip facing up. Still, the handwriting is dark.

[Evaluation of writing feeling]
Each ballpoint pen containing the inks of Examples 12 to 26 and Reference Examples 1 to 3 was used to write on the same type of test paper as the paper used in the evaluation of the ink stability, and the writing feeling was evaluated. The evaluation criteria were as follows.
A: Very smooth writing feeling is obtained without catching.
B: A smooth writing feeling is obtained although there is a feeling of being slightly caught.
C: There is a sticky feeling, and a smooth writing feeling cannot be obtained.

Table 5 shows the above evaluation results.

This application is accompanied by priority claims based on Japanese patent applications, Japanese Patent Application Nos. 2021-106273 and 2021-106616, each of which has a filing date of June 28, 2021. Japanese Patent Application No. 2021-106273 and Japanese Patent Application No. 2021-106616 are incorporated herein by reference.

Claims

An ink composition comprising a coloring pigment, a luster pigment, microcapsule particles, a shear thinning agent, and water,
Based on the total mass of the ink composition, the content of carbon black in the coloring pigment is 0 to 2.0% by mass, and the content of the luster pigment is 0.1 to 2.0% by mass. , The water-based ink composition for a ballpoint pen, wherein the content of the microcapsule particles is 1.5 to 10 times the content of the glitter pigment.
The colored pigment contains carbon black and an organic pigment,
The content of the carbon black is 0.1 to 2.0% by mass, and the content of the organic pigment is 2 to 10% by mass, based on the total mass of the ink composition. A water-based ink composition for ballpoint pens.
The water-based ink composition for a ballpoint pen according to claim 2, wherein the content of the organic pigment is equal to or more than 15 times the content of the carbon black, based on the total mass of the ink composition.
Based on the total mass of the ink composition, the relationship between the carbon black content (X), the organic pigment content (Y), and the bright pigment content (A) is 0.1 ≤ [ 4. The water-based ink composition for a ball-point pen according to claim 2, wherein (X)+(A)]/(Y)≤1.
Based on the total mass of the ink composition, the sum of the carbon black content, the organic pigment content, the glitter pigment content, and the microcapsule particle content is 5% by mass or more. The water-based ink composition for ballpoint pens according to claim 2 or 3, which is 20% by mass or less.
The water-based ink composition for ballpoint pens according to claim 1 or 2, further comprising a polyoxyethylene polyoxypropylene alkyl ether.
The water-based ink composition for a ballpoint pen according to claim 6, wherein the color pigment contains an organic pigment having a phthalocyanine skeleton or a dioxazine skeleton.
The water-based ink composition for a ballpoint pen according to claim 6, wherein the mass ratio of said bright pigment and said color pigment is 1:1 to 1:10.
The water-based ink composition for a ballpoint pen according to claim 6, wherein the polyoxyethylene polyoxypropylene alkyl ether has an HLB value of 10 or more and less than 15.
7. The water-based ink composition for a ballpoint pen according to claim 6, wherein the content of said polyoxyethylene polyoxypropylene alkyl ether is 0.1% by mass or more and less than 4.0% by mass, based on the total mass of said ink composition. thing.
The water-based ink composition for a ballpoint pen according to claim 6, wherein at least part of said polyoxyethylene polyoxypropylene alkyl ether is present on the surface of said color pigment.
The water-based ink composition for a ballpoint pen according to claim 1 or 2, wherein the microcapsule particles encapsulate a lipophilic compound that is liquid or solid under normal temperature and normal pressure.
The water-based ink composition for a ballpoint pen according to claim 12, wherein the lipophilic compound is one or more selected from the group consisting of aromatic hydrocarbons, esters, ketones, higher alcohols and ethers.
A ballpoint pen containing the water-based ink composition for a ballpoint pen according to claim 1 or 2.
A ballpoint pen refill containing the water-based ballpoint pen ink composition according to claim 1 or 2.